This invention relates to carbon dioxide (CO2) detectors. More particularly, it refers to a housing containing CO2 colorimetric indicator paper, the housing attached to a bulb style esophageal detector device for detecting CO2 levels in the aspirated air from a patient following intubation.
U.S. Pat. No. 4,691,701 describes an early portable CO2 detector in the form of a transparent disc containing a chemical substance exhibiting a color change indication when exposed to carbon dioxide from a patient.
U.S. Pat. Nos. 5,197,464 and 5,291,879 describe methods of monitoring CO2 levels in a patient using a reversible indicator solution so that the indicator changes color continuously with the breathing of a patient.
Other references that include references to CO2 color change devices are U.S. Pat. Nos. 4,790,327; 4,928,687; 4,994,117; 5,005,572; 5,166,075, 5,179,002; 5,846,836 and 5,965,061.
A critical step in the intubation of a patient is a determination that the intubation tube or endotracheal tube is placed in the trachea and not in the esophagus. If the tube is in the esophagus, there is no return of CO2 beyond ambient levels from a patient""s aspirated air. If the tube is in the trachea, CO2 will be present up to about five percent concentration.
The trachea is substantially rigid because it is made up of C-shaped ridges of rigid cartilagineous rings joined vertically by fibro elastic tissue. The esophagus, on the other hand, is a fibro muscular tube having no intrinsic structure to maintain any rigidity. The use of a bulb at the end of the often used and well known esophageal detector device is based on the principal that the esophagus will collapse when a negative pressure is applied to its lumen, whereas a trachea will not because of its greater rigidity. Normally, an intubation tube is placed in the patient""s trachea and a soft rubber bulb is compressed and then attached at one end of the intubation tube. The tube will aspirate gas freely from the patient""s lungs without any resistance if the tube is in the trachea when the bulb is released. If the intubation tube is in the esophagus, the negative pressure caused by the bulb will cause the esophagus to collapse and the bulb will stay compressed. Misplacement of the intubation tube can affect the mortality of the patient.
Since it is common in emergency situations for less highly skilled technicians to apply intubation tubes for maintaining the patient""s airway, it is important to have a portable single patient device confirming the proper initial placement of the intubation tube. A CO2 detector serves this purpose. Although CO2 detector""s exist, the use with an esophageal detector device to provide confirmation of proper intubation tube placement is not known. Such a combined device exhibiting ease of use, low cost and connection to existing breathing apparatus is needed.
The invention described herein is an improvement over existing esophageal detector devices used for verifying placement of an intubation tube in a patient""s trachea. The CO2 detector employed in this invention has an easily mountable colorimetric indicator paper that changes color in response to CO2 levels in aspirated air from a patient. It is easily mountable in communication with an esophageal detector device housing, is lightweight and gives easily readable and reliable CO2 detection to confirm intubation tube placement in the patient""s trachea.
The preferred CO2 detector is a clear plastic disc mounted on a rim. Indicator paper is mounted on the inside surface of the plastic disc. Backing paper on the indicator paper is removed prior to use of the detector by pulling on the backing paper protruding from a port in a cylindrical housing on which the rim of the disc is mounted. The backing paper insures that the indicator paper will not be exposed prior to use. The disc rim is glued or heat welded to the esophageal detector housing. A baffle is mounted on an inner wall of the esophageal detector housing between a first and second axially positioned port. The first port is connected to an elastomeric bulb and the second port is connected to an intubation tube adapter leading to an intubation tube for insertion in a patient""s trachea. Provided the tube is properly placed, the aspirated air from the patient will cause a color change on the colorimetric indicator paper viewed through the clear plastic cover of the CO2 detector of this invention.